CDC Survey Puts Autism at 4.5% of Kids. A 12-Cohort Screening Study Found No Rise.

Two papers eight days apart look like they disagree. Both point to detection, and they measure different things: what parents were told, and what screening every child finds.

Two autism prevalence papers came out eight days apart. On September 22, CDC researchers reported in Pediatrics that parent-reported autism among US children aged 3–17 rose from 3.1% to 4.5% between 2019–2020 and 2023–2024. On September 14, a JAMA Pediatrics study that screened whole cohorts of South Korean schoolchildren found no statistically significant increase or decrease across 12 consecutive birth years.

The turn: they measure different things

The US figure counts diagnoses: “All diagnoses are based on parents reporting what they have been told by a physician or other health care professional.” The Korean study screened every child entering elementary school and fully assessed those who screened positive, so it estimates occurrence whether or not anyone had been diagnosed. Both sets of authors explain the numbers the same way. The CDC team says the increases “could be related to earlier detection and awareness.” The Korean team says “detection-related factors may contribute substantially to reported increases.”

For a clinic, diagnoses are the number that drives referrals. For a state agency explaining ABA spending growth, “detection” cuts both ways. It can mean children who were always there are finally being found, or that the diagnostic net has widened. The Korean paper supports the first reading in one group: girls with autism “were disproportionately represented among previously undiagnosed cases identified in general education settings” and had “substantial unmet clinical needs.”

The findings

  • US (Zablotsky et al., NCHS, National Health Interview Survey), adjusted: any developmental disability 16.7% to 20.5%, ADHD 9.5% to 12.0%, autism 3.1% to 4.5%, learning disability 7.6% to 8.8%, other developmental delay 5.5% to 6.4%. There was no significant change in intellectual disability.
  • Korea (Kim, Fombonne, Leventhal et al.): more than 62,000 children born 1998–2010, screened at age 7. 2,077 screened positive and 881 completed full assessment (ADOS, ADI-R, cognitive testing, record review). Cumulative incidence ranged from 1.9% to 3.2%, and prevalence from 2.0% to 3.4%.

The limits

The US estimate rests on parent report, and the abstract gives no sample size or data on severity or services. The Korean cohorts end with children born in 2010, before the period the US survey covers, and fewer than half of the screen-positive children completed assessment. Each is one country, and neither measures ABA use.

What you must know or do

  • Owners planning capacity: forecast from your own referral data, not from either headline. The US figure tracks diagnoses, which is what reaches your intake line.
  • Intake leads: count how many of your last 50 new clients are girls, and where each referral came from. If school-age girls in general education are missing, that's the group the Korean study found undiagnosed.
  • If a payer or legislator cites growth: both papers attribute the rise to detection. Neither shows that autism itself has become more common.